A rotorcraft, such as a tiltrotor or helicopter, includes at least one rotor mast for driving the rotor hub to transmit forces to the attached blades. One of the main overall goals in rotorcraft design is to make the rotorcraft as light as possible. Despite this desire to make everything on a rotorcraft as light as possible, it is very difficult to reduce the weight of the rotor mast. The difficulty in reducing the weight of the rotor mast is due to the tremendous loads carried through the rotor mast. Not only must the rotor mast transmit the torque from the transmission to the rotor hub, but the rotor mast must transmit the lift force created by the rotating blades to carry the full weight of the rotorcraft. In addition, the rotor mast is subject to lateral loads created by the movement of the rotorcraft as well as the wind. In order to accommodate these forces, existing rotor masts are made of steel.